Answered: array issue qa-includepagesquestion-view.php on line 1131

In PHP 7.4 they have changed the way to report this, if you use PHP 7.3 this notice is not shown.

Use PHP's @ control operator to hide it.

Change line 1131 as follows:

isset($in'notify']) ? $in'notify'] : qa_opt('notify_users_default'), $in'email'], @$errors'email'], $prefix);

to

isset($in'notify']) ? $in'notify'] : qa_opt('notify_users_default'), @$in'email'], @$errors'email'], $prefix);